Epidemiologic studies indicate that breastfeeding is associated with reduced risk of developing components of the metabolic syndrome. Breastfeeding and metabolic risk factors in childhood are both socially patterned, however, and it is likely that the unconfounded effects of breastfeeding can be convincingly demonstrated only in a large randomized controlled trial. This application is based on the 9-year follow-up of 17,046 healthy infants who originally participated in the Promotion of Breastfeeding Intervention Trial (PROBIT), a cluster-randomized trial in the Republic of Belarus. The intervention produced two groups with substantially different exposure to prolonged exclusive breastfeeding, providing a unique opportunity to test, in an intention to treat analysis, the effect of breastfeeding promotion on the metabolic syndrome in childhood. The overall goal of this application is to investigate the influence of a breastfeeding promotion intervention on the development of the metabolic syndrome, its components, and adiponectin levels in childhood within the setting of a randomized controlled trial. This application takes advantage of the largest trial ever undertaken in the area of human lactation. Its feasibility is demonstrated by the high (> 80%) follow up rates already achieved at 12 months and 6.5 years. The trial was carried out in Belarus because maternity hospital practices there are similar to those in North America and Western Europe 20 to 30 years ago and thus provide a greater potential contrast between intervention and control study sites. Although different in many sociocultural respects from the United States, Belarus is a relatively developed country. The results of the proposed study are therefore likely to inform policy in the US and elsewhere. By following up the already enrolled PROBIT participants at 9 years of age, and with already secured co-funding from the Canadian Institutes of Health Research and the European Union, the proposed project provides a relatively economical way to answer robustly scientific questions of major public health importance regarding the precursors of the metabolic syndrome in children. [unreadable] [unreadable] [unreadable] [unreadable]